1. Field of the Invention
The present invention relates to an armrest device for a chair (generally, an office chair) which is capable of changing a direction of an armrest of the chair.
2. Prior Art
There has been proposed an armrest device for a chair, e.g. by Japanese Provisional Patent Publication (Kokai) No. 9-299186, which comprises a support for an armrest, a pair of fore and rear fixed supporting shafts disposed on the support, a pair of front and rear guiding grooves disposed on the armrest for engaging with the fixed supporting shaft, respectively. On this occasion, the fore guiding groove comprises two continuous grooves oriented in two directions, and the rear guiding groove is formed linearly in the longitudinal direction.
According to the prior art, the longitudinal moving position of the armrest is regulated depending on the engagement relationship between the rear fixed supporting shaft and the rear guiding groove. The armrest is moved forward while engaging one of the fore guiding grooves with the fore fixed supporting shaft, thereby causing the armrest to be automatically rotated with the rear fixed supporting shaft as a center, which causes the direction of the armrest to be changed.
According to the prior art, changing the direction of the armrest requires to move the armrest longitudinally; therefore, changing the direction of the armrest e.g. from the right side to the left side requires to move the armrest rearward at once, and then forward again (simultaneously, the armrest is rotated). This makes the armrest direction changing operation troublesome.